rem (root em) units

- CR

Type of unit similar to em, but relative only to the root element, not any parent element. Thus compounding does not occur as it does with em units.

IE

  1. 5.5 - 8
  2. 9 - 10
  3. 11

Edge

  1. 12 - 81
  2. 83

Firefox

  1. 2 - 3.5
  2. 3.6 - 75
  3. 76
  4. 77 - 78

Chrome

  1. 4 - 81
  2. 83
  3. 84 - 86

Safari

  1. 3.1 - 4
  2. 5 - 13
  3. 13.1
  4. TP

Opera

  1. 9 - 11.5
  2. 11.6 - 67
  3. 68

iOS Safari

  1. 3.2
  2. 4 - 4.3
  3. 5
  4. 6 - 13.3
  5. 13.4

Opera Mini

  1. all

Android Browser

  1. 2.1 - 4.4.4
  2. 81

Blackberry Browser

  1. 7
  2. 10

Opera Mobile

  1. 10 - 11.5
  2. 12 - 12.1
  3. 46

Chrome for Android

  1. 81

Firefox for Android

  1. 68

IE Mobile

  1. 10
  2. 11

UC Browser for Android

  1. 12.12

Samsung Internet

  1. 4 - 10.1
  2. 11.1

QQ Browser

  1. 10.4

Baidu Browser

  1. 7.12

KaiOS Browser

  1. 2.5
Resources:
Article on usage
REM Polyfill